A large blanket, usually thick and comfortable, that is used to cover a man as he jerks off. Usually done during the night in private, but can also be done with a companion depending on how big the blanket is. Also, usually the blanket has a white side to it, to better hide the cum on the blanket.

"Man I'm so tired, i think i'm going to go do a quick one in my naked blanket and then pass out"